1. Field of the Invention
The invention relates to a polyester resin, and more particularly to a polyester resin with heat-resistance and transparency and a fabrication method thereof.
2. Description of the Related Art
Generally, there are three conventional methods in which polyester resin is fabricated: interfacial polymerization, solution polymerization and melt polymerization. The interfacial polymerization method is performed at an interface between an organic solution and a water solution which are incompatible with each other. A polyarylate (PAR) with a high molecular weight can be fabricated using the interfacial polymerization method. However, disadvantages of using the interfacial polymerization method include: having complicated processes; relatively large power and water requirements; and requirement to use volatile organic compounds (VOC). Therefore, the interfacial polymerization method is environmentally un-friendly. Meanwhile, using the solution polymerization method to fabricate polyarylate (PAR) requires an organic solvent. A disadvantage of using the solution polymerization method includes difficulty in efficiently enhancing the molecular weight of the fabricated polyarylate (PAR). Therefore, physical and mechanical properties of the polyarylate (PAR) fabricated by the solution polymerization method are unsatisfactory.
U.S. Pat. No. 5,164,478 discloses utilizing a melt polymerization method to fabricate a polyester resin. In this method, a diphenol monomer and a diacid monomer are used to form the polyester resin by high temperature melt polymerization. However, the high temperature (above 250° C.) process step required for polymerization of the polyester resin, results in a yellowish-colored polyester resin. Additionally, the diphenol monomer used in this method is a bisphenol A monomer, which does not effectively enhance the glass transition temperature (Tg) of the polyester resin. Thus, hindering high heat-resistance and transparency of the fabricated polyester resin.
Therefore, a polyester resin and a fabrication method thereof which can achieve high heat-resistance and transparency are desired.